Remove _initialized check from DrawableGameComponent.GraphicsDevice

Initially i put the check there as was implemented by @Aztherion.

I did some testings and found that XNA doesn't enforce any similar test.
After all GraphicsDevice is already initialized by Game. It's logical
that someone might want to do some non-content initialization on the
constractor of DrawableGameComponent based on values from
GraphicsDevice.
Merge remote-tracking branch 'upstream/develop' into nKast_DrawableGameComponent_GraphicsDevice
Merge remote-tracking branch 'upstream/develop' into nKast_DrawableGameComponent_GraphicsDevice
Merge remote-tracking branch 'upstream/develop' into nKast_DrawableGameComponent_GraphicsDevice
Merge pull request #2064 from nkast/nKast_DrawableGameComponent_GraphicsDevice

Remove _initialized check from DrawableGameComponent.GraphicsDevice